Barcelona have identified Athletic Club Bilbao centre-back Aymeric Laporte as their top candidate to bolster Luis Enrique's backline during the summer transfer window, according to Mundo Deportivo. The La Liga giants, nevertheless, are working on alternatives such as Chelsea starlet Andreas Christensen and PSG's much-coveted star Marquinhos due to competition from Manchester City to secure the French centre-back.

Ariedo Braida, Barcelona's international adviser, confirmed last week that signing a defender to partner Gerard Pique in the hear of the defence was the side's number one priority ahead of next season due to the advanced age of the side's current rear guard, with Jeremy Mathieu, Javier Mascherano and Thomas Vermaelen all the wrong side of 30.

The erratic performance of Mathieu during the 2-2 draw against Villarreal last weekend has further proven Barcelona's need to bolster the position. The former Valencia centre-back and Vermaelen have both failed to fill the gap left by Carles Puyol during their first two seasons at the club, and Marc Bartra has fallen out of favour for Luis Enrique.

Mundo Deportivo has now revealed Barcelona technical secretary Robert Fernandez has made a large list of candidate to address the issue in the summer, with Laporte at the very top of the pile.

The story claims Barcelona see the 21-year-old defender as the perfect candidate as he would not need time to adapt to La Liga. However, the fly in the ointment comes in recent reports that Pep Guardiola is keen to lure him to Manchester City, while Athletic Club will not negotiate his departure for anything lower his €50m (£39.2m, $56.1m) release clause.

Mundo Deportivo claims Barcelona have therefore identified a number of alternatives as they are aware of the stiff competition they will face to secure a centre-back, with City, Chelsea and ManchesterUnited are also desperately looking to bolster the position in the summer.

Catalan publication insists that Barcelona scouts have been impressed by the impressive development of Christensen during his loan spell at Borussia Monchengladbach, but it looks unlikely that Chelsea, who owns his rights, will negotiate the exit of the 19-year-old defender.

Marquinhos is the third name on the Barcelona list. but PSG are again seemingly unwilling to negotiate his departure.

Mundo Deportivo, meanwhile, claims Barcelona have ended their interest in Everton's John Stones as they consider his price range out of their reach, and also have doubts about his adaptation to Spanish football. His teammate Funes Mori, however, could be an alternative for Barcelona officials, alongside Milan's Alessio Romagnoli, Juventus duo Leonardo Bonucci and Daniele Rugani, Olympique de Lyon's Samuel Umtiti and Sassuolo's Sime Vrsaljko.